A power control system comprising a laser driver that receives a data signal, and responsive to a modulation control signal and a bias control signal, processes the data signal to drive a laser to generate an optic signal that represents the data signal. A monitor photodiode configured to receive the optic signal and generate a monitor photodiode signal.

A modulation control path, that processes a monitor photodiode signal and a reference signal, including at least one filter and at least one mixer. The modulation control path generates a modulation control signal. A bias control path, that processes the monitor photodiode signal and the reference signal, that includes at least one filter and at least one average weighting module to generate a modulation control signal. The bias control path and the modulation control path processing reduces the effect of the error in the monitor photodiode signal.

A second optical modulator is provided between a semiconductor laser and a first optical modulator. Further, a second optical waveguide branched from a first optical waveguide is provided between the semiconductor laser and the second optical modulator, and a light receiving element which converts received laser light into a second electrical signal is provided at an end of the second optical waveguide. Furthermore, the second optical modulator adjusts a light intensity of the laser light entering the first optical modulator to a fixed light intensity, based on data transmitted as the second electrical signal. Still further, the first optical modulator modulates the laser light based on data transmitted as a first electrical signal, and converts the first electrical signal into an optical signal.

An object is to output an optical signal accurately corresponding to a data signal. A pluggable optical module (100) includes a pluggable electric connector (11), a control unit (12), an optical signal output unit (13), and a pluggable optical receptor (14). The pluggable electric connector (11) can communicate a modulation signal (MOD) and a control signal (CON1) with an optical communication apparatus (92). The optical signal output unit (13) outputs an optical signal (LS) modulated by the modulation scheme by the control signal (CON1) in response to the modulation signal (MOD). The pluggable optical receptor (14) is configured in such a manner that an optical fiber (91) is insertable into and removable from the pluggable optical receptor (14). The pluggable optical receptor (14) can output the optical signal (LS) output from the optical signal output unit (13). The control unit (12) controls the optical signal output unit (13) to output the optical signal (LS) of a modulation amplitude set corresponding to the modulation signal (MOD) in the modulation scheme specified by the control signal (CON1).

A transmitter with at least one optical modulator adapted to modulate the optical signal output by a laser source to generate a modulated optical signal, wherein the optical signal output by the laser source is tapped and supplied to a monitoring circuit comprising an optical front end configured to select signal components of the tapped modulated optical signal and to convert the selected signal components of the tapped modulated optical signal into analog signals, and comprising at least one analog-to-digital converter, ADC, adapted to perform equivalent-time sampling of the analog signals to provide digital signals processed by a processing unit to monitor signal quality of the modulated optical signal.

A method for setting a pluggable optical transceiver, includes: amplifying, with an amplifier, an electrical signal being input to the pluggable optical transceiver from an external device to which the pluggable optical transceiver is mounted, and outputting the amplified electrical signal as a drive signal of an optical modulator; modulating light input from a light source with the optical modulator, based on the drive signal, and outputting the modulated light; monitoring amplitude of the drive signal; and executing a control sequence being set in advance for at least one of the amplifier and the optical modulator when detecting that amplitude of the drive signal exceeds a reference value being set in advance.

An apparatus at least includes a processor to, after a first signal passes through a narrowband photodetector, perform frequency mix of the first signal with a first reference signal and a second reference signal respectively and perform noise reduction, to obtain a first detection signal and a second detection signal. The first signal is obtained after a measurement signal passes through a filtering module of an optical transmitting end, the measurement signal being transmitted in a path of multiple branches, signals not transmitted in other paths of the multiple branches, a frame structure of the measurement signal including at least one two-tone signal, two tones in the two-tone signal having a fixed tone interval. The processor is to calculate group delays at multiple frequency bins according to the first detection signal and the second detection signal; and determine a phase response of the filtering module of the optical transmitting end in the path according to the group delays at multiple frequency bins.

An apparatus at least includes a processor to, after a first signal passes through a narrowband photodetector, perform frequency mix of the first signal with a first reference signal and a second reference signal respectively and perform noise reduction, to obtain a first detection signal and a second detection signal. The first signal is obtained after a measurement signal passes through a filtering module of an optical transmitting end, the measurement signal being transmitted in a path of multiple branches, signals not transmitted in other paths of the multiple branches, a frame structure of the measurement signal including at least one two-tone signal, two tones in the two-tone signal having a fixed tone interval. The processor is to calculate group delays at multiple frequency bins according to the first detection signal and the second detection signal; and determine a phase response of the filtering module of the optical transmitting end in the path according to the group delays at multiple frequency bins.

A method for setting a pluggable optical transceiver, includes: amplifying, with an amplifier, an electrical signal being input to the pluggable optical transceiver from an external device to which the pluggable optical transceiver is mounted, and outputting the amplified electrical signal as a drive signal of an optical modulator; modulating light input from a light source with the optical modulator, based on the drive signal, and outputting the modulated light; monitoring amplitude of the drive signal; and executing a control sequence being set in advance for at least one of the amplifier and the optical modulator when detecting that amplitude of the drive signal exceeds a reference value being set in advance.

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

An object is to output an optical signal accurately corresponding to a data signal. A pluggable optical module (100) includes a pluggable electric connector (11), a control unit (12), an optical signal output unit (13), and a pluggable optical receptor (14). The pluggable electric connector (11) can communicate a modulation signal (MOD) and a control signal (CON1) with an optical communication apparatus (92). The optical signal output unit (13) outputs an optical signal (LS) modulated by the modulation scheme by the control signal (CON1) in response to the modulation signal (MOD). The pluggable optical receptor (14) is configured in such a manner that an optical fiber (91) is insertable into and removable from the pluggable optical receptor (14). The pluggable optical receptor (14) can output the optical signal (LS) output from the optical signal output unit (13). The control unit (12) controls the optical signal output unit (13) to output the optical signal (LS) of a modulation amplitude set corresponding to the modulation signal (MOD) in the modulation scheme specified by the control signal (CON1).